This show was decent, but like most people, I find the last few seasons to be really... out there and sometimes hard to watch. I mean I liked all the characters, including Urkel, but the show changed. Plots would be too out-there and it wasn't really something kids would get. The show still focused on the family but not nearly as much as the earlier seasons. But I don't think Urkel killed the series entirely, as some do. I just think he, his character, made it science fictiony.
So, my overall grade for this show is about a C+/B-. Good in some places, not so good in others